A conventional cathode ray oscilloscope is used to provide a display on the screen of a cathode ray tube of the waveform of an input signal. It is also conventional for the oscilloscope to display one or more cursors representing selected signal magnitude levels or the time of occurrence of selected events. In addition, conventional oscilloscopes display alphanumeric text information, typically along the upper and lower edges of the CRT screen, representing the operating mode and settings of the oscilloscope. This text information might include information relating to the value of the parameter represented by a cursor or by the distance between two cursors. For example, where the cursor represents signal magnitude, e.g. voltage, the text information might indicate the value of the signal magnitude, relative to a datum level that is represented by the position of the cursor, and if two cursors are displayed at positions representing different magnitude values, the text information might indicate the difference between the values represented by the cursor positions respectively. Where a cursor represents time, the text information might indicate the interval between a trigger event and the time represented by the cursor position, and where two cursors are displayed the text information might indicate the duration represented by the distance between the cursors.
Using a conventional oscilloscope that displays a waveform signal, text information and one or more cursors, it is necessary for the operator to shift attention between the cursors and the text information in order to interpret the significance of features of the waveform.